Wednesday, September 22, 2010

A Rare Find- Unbiased, Accurate News!

A recent news article in Science Daily highlights a concise study on light pollution on bird species, and its negative impacts on their mating habits. Science has measured light pollution before, and has even touched upon the issue of urban noise on song birds (Marshall and Mockford, 2009). The study referenced in Science Daily, conducted by Borgström et al., looks at the mating patterns of 5 bird species in a new light. Researchers in Germany observed 5 bird species’ mating patterns in the forest, and around urbanized areas to conclude that artificial light makes certain species of birds sing earlier.

The news article includes many quotes from the original study, to back up its statements. It starts off by giving an accurate- albeit skimpy- summary of the key points of the study. It states correctly that four of the five species of birds living in urban areas studied, started dawn calls earlier than their forest dwelling counterparts. The Chaffinch exhibited a less significant response from night lighting than the other four species as acknowledged in the news article (Science Daily, 2010). This outlier in the study was not explained by the researchers. Although the data is very clear, an explanation of the outlier would have strengthened the validity of the researchers. The strength of the data, and the lack of response in Chaffinch, is illustrated in the graph below.

The article goes on to describe changes in mating habits, and states that “Females near street lights laid their eggs on average a day and half earlier.” (Science Daily) This statement accurately summarizes most of the 800 words of in-depth data about the change in mating habits of birds found in the original study. What the article left out, is that the researchers has a %95 confidence interval for their data which also cross referenced their research with “a study on captive blue tits that showed that females advanced their laying date when exposed to artificially extended photoperiods.” (Borgström et al., 2010) Had the article included this number, it would have strengthened their statement. It also could have used research from another source to back up it’s claims, rather than relying solely on one source. The researchers used research from almost 40 sources to back up their statements, thus creating a more credible paper.

Another important correlation mentioned in the news article is that“males near lights at the forest's edges were more successful in... [siring] offspring with females other than their primary social partners.”(Science Daily) In fact, the research shows that males living near lights were an average of two times more likely to make with an extra partner.(Borgström et al) As shown in the graph below, adult males were more likely to sire extra-pair offspring than yearlings. The researchers try to explain this data with their theory that adult males are more successful at extra-pair mating because they sing earlier in the morning than yearlings- this effect is pronounced more when near artificial lighting. The researchers compared their theory with a study done in the United States which concluded that “early singing males were larger and had relatively long flight feathers.”(Dolan et al., 2010) This comparison helps to validate their inference.

Although much primary source information was condensed into a few lines, the news article did get direct quotes from one of the researchers. Dr Bart Kempenaers was quoted saying:

Earlier singing during the morning may come at a cost to males... females may use early singing as a cue reflecting male quality. Light pollution may disrupt the link between the cue -- early singing -- and male quality, so that females would end up having their offspring sired by lower-quality males. These costs -- if they exist -- will be hard to measure.

Although not mentioned in the article, the researchers go on to conclude that because females exposed to artificial light laid their eggs earlier, their offspring may be off synch with the peak food demand. (Borgström et al) Presumably the birds timed their mating (through evolutionary means) to match the peak demand of food, and having offspring early back-steps this evolutionary advantage.

As I’m certain is made quite clear from this blog post, the news article left out much valuable information found in the primary source. It did, however, provide a very accurate summary of the research paper that would attract an audience who only want to know the core of the research. No information was misrepresented in the secondary source, nor were any facts unreferenced. In fact, the news article included pertinent information about the study that was not included in the primary source, such as direct quotes from one of the affiliated researchers, Dr. Bart Kempenaers. However, including other references would have strengthened the article’s credibility. In conclusion, the article was unbiased, valid, and was fairly credible in it’s summary of the German study which had very strong claims coming from clear data, and numerous references.

Marshall, R., Mockford, E. “Effects of urban noise on song and response behaviour in great tits.” The Royal Society, May 7, 2009. Web. September 20, 2010. http://rspb.royalsocietypublishing.org/content/276/1669/2979